1. Field of the Invention
The present invention relates to an information processing method and an apparatus therefor, which are applied to a file system in a computer system or a distributed file system in a high-speed network.
2. Related Background Art
(1) When an individual person is to conventionally perform a certain job for a file stored in an information storage (e.g., a file system in a computer system) between remote locations such as locations between his home and an office, identical copies of necessary files and the like must be stored in information storages at these remote locations, and data is manually exchanged between these information storages using a portable recording medium such as a floppy disk (FD) to maintain consistency therebetween.
(2) In a conventional distributed file system, file data to be read out and written are stored in a secondary storage (disk) connected to one server in a network, and the data is read out from or written in the secondary storage through the network. To compensate for the low access speed of the secondary storage, a plurality of secondary storages are arranged in parallel with each other like a disk array.
However, in the prior art (1), every time another information processing apparatus is used, the files are recorded in a portable recording medium and stored in the external storage of this information processing apparatus. At this time, when the number of files is small, file processing for specific files can be easily managed. However, when the number of files increases, selection of files to be recorded is complicated. The user may forget to copy a modified file on the recording medium. Therefore, consistency of files may not be maintained.
The prior art (1) has the following drawbacks because consistency and matching maintenance of the contents of files between a plurality of locations must be manually performed.
An operation for maintaining consistency and matching is cumbersome. PA1 The failure in matching maintenance may occur due to a manual operation error. PA1 The medium has a low input/output speed. PA1 The medium has a small storage capacity. PA1 The medium cannot be used if the quantity of information to be stored exceeds a certain quantity. PA1 The medium cannot have a sufficiently high processing speed in a job using a file.
For example, as shown in FIG. 8, a series of files A, B, . . . are present in two information storages 100 and 101 at locations a and b. When the contents of the file A in the information storage 100 at the location a are modified at a given time, the following series of operations must be performed. Only the modified file A is selected, and its contents are stored in a floppy disk FD. This floppy disk FD is carried to the location b, and the contents of the corresponding file in the information storage 101 are updated.
Referring to FIG. 8, the files A and B have entities Aa and Ba of the files A and B at the location a and have entities Ab and Bb of the files A and B at the location b.
Jobs necessary for maintaining consistency and matching upon (1) a modification, (2) an addition, and (3) a deletion of a file at one location will be described below.
(1) Modification of Contents of File
Assume that the entities Aa and Ab of the file A which have identical contents are present at the locations a and b, and that the contents of the entity Aa are modified at a given time and the location a. When a user then moves to the location b, he must modify the entity Ab for the modification at the location a before the contents of the file A are referred to or modified.
(2) Addition of File
When the entity Ba which is present at neither the location a nor the location b is formed at the location a, the entity Bb must be formed at the location b when the user moves to the location b.
(3) Deletion of File
Assume that entities Ca and Cb of a file C which have identical contents are present at the locations a and b. When the entity Ca is deleted at a given time and the location a, the entity Cb must be deleted at the location b when the user moves to the location b.
The arbitrary number of combinations of arbitrary jobs of all the jobs are assumed in a practical job.
As one method of avoiding such a job, all the files may be stored in a portable recording medium such as a floppy disk, and all systems may not have any file. However, this medium generally has one or both of the following drawbacks as compared with a storage generally used in a system:
According to this method, even if a file is temporarily copied in a storage in a system, and a job is performed using the file, the following problems are posed:
In the prior art (2), when a plurality of secondary storages are provided, all the secondary storages must be connected to one server. In addition, since only one data line is available between the server and a client, a narrow path is formed by the network to fail to obtain a sufficiently high input/output speed.